The present invention relates to electronics packaging, and more specifically relates to an enclosure for holding and interconnecting individual modules so as to form an integrated subsystem of a data processing system.
Midrange and mainframe data processing systems are often physically packaged in one or more vertical racks. Each rack commonly has a standard width and a defined unit height for mounting enclosures having the standard width and an integer multiple of the unit height. Each enclosure may contain a subsystem of the entire system: a central electronics complex (CEC), mass storage facilities, communications equipment, and so forth.
Mass storage typifies one class of subsystems. Such a subsystem has multiple functional modules--such as multiple small fixed-disk drives or backup tape drives, or a combination of the two--which couple to the remainder of the system essentially as a single unit, such as by a common data bus. The system may not even be aware of what individual functional modules comprise the subsystem.
Such a subsystem should also include all support modules required by the functional modules, so that the subsystem can be inserted into and removed from the system as an integral unit without requiring any changes to the remainder of the system. For example, the subsystem itself should provide the power in a form and amount adequate to supply all the functional modules, requiring only raw power from the rack. Backup or uninterruptible power may also be necessary. The subsystem itself may be required to collect data from the functional modules into a single bus, or to convert it to another electrical level or even to an entirely different bus or protocol.
A subsystem of this type also commonly comprises functional modules requiring relatively large amounts of power. Therefore, the subsystem itself should provide adequate cooling for all of the modules located in it.
Packaging for such subsystems is usually designed on an ad-hoc basis for each different subsystem, even within the same overall system. This proliferates part numbers and tooling for the system, increasing the expense and complexity of manufacturing the system.
Moreover, different customers of the same system--or the same customers at different times--require subsystems of the same type which are customized to their particular needs. For example, one customer may need a mass-storage subsystem having a maximum data capacity, regardless of any other consideration. Another may need less capacity, but must have at least one removable-medium device for transfer to another system for backup. One customer may not require any uninterruptible power, but another may need enough emergency power to complete an orderly shutdown, and yet another may wish to remain fully operational through longer periods of primary power loss. Interfaces to the system may differ for different customers. One may wish to interconnect the subsystem to a CEC in the same rack, requiring only repowering or level conversion of the data signals. Another may wish to integrate an I/O processor or controller into the subsystem itself, then communicate to the CEC via another protocol or bus. A third may desire to convert the output of a controller to another form suitable for transmission to the remainder of the system over longer distances.